The first stage is modifying the screening and assessment instruments (ADI-R and ADOS-2) for use with deaf children. This will involve choosing the most promising screening instrument (SRS-2) based on the systematic review and the expertise of a review panel, which contains experts and public and patient involvement (PPI). This phase of the study seeks a wide range of user (parents/ carers and young people) views and experiences about the symptomatology and presentation of deaf children with autism, comparing this to hearing children with autism, and deaf children without autism.